test: add path boundary coverage

tests/test_path_boundaries.py

@@ -0,0 +1,122 @@
+from __future__ import annotations
+
+import tempfile
+import unittest
+from pathlib import Path
+
+from agent_rules_kit.discovery import (
+    InstructionFile,
+    InstructionFileKind,
+    discover_instruction_files,
+)
+from agent_rules_kit.init_plan import InitPlanAction, build_init_plan
+from agent_rules_kit.init_write import BASELINE_AGENTS_CONTENT, write_init_files
+
+
+class PathBoundaryTests(unittest.TestCase):
+    def test_discovery_reports_repository_relative_paths(self) -> None:
+        with tempfile.TemporaryDirectory() as temporary_directory:
+            repository = Path(temporary_directory)
+            cursor_rule = repository / ".cursor" / "rules" / "agent.mdc"
+            cursor_rule.parent.mkdir(parents=True)
+            cursor_rule.write_text("Cursor rule\n", encoding="utf-8")
+
+            self.assertEqual(
+                discover_instruction_files(repository),
+                (
+                    InstructionFile(
+                        path=".cursor/rules/agent.mdc",
+                        kind=InstructionFileKind.CURSOR_RULE,
+                    ),
+                ),
+            )
+
+    def test_discovery_ignores_backup_and_temporary_files(self) -> None:
+        with tempfile.TemporaryDirectory() as temporary_directory:
+            repository = Path(temporary_directory)
+            (repository / "AGENTS.md.agent-rules-kit.bak").write_text(
+                "backup\n",
+                encoding="utf-8",
+            )
+            (repository / ".AGENTS.md.agent-rules-kit.tmp").write_text(
+                "temporary\n",
+                encoding="utf-8",
+            )
+
+            self.assertEqual(discover_instruction_files(repository), ())
+
+    def test_init_plan_only_targets_root_agents_file(self) -> None:
+        with tempfile.TemporaryDirectory() as temporary_directory:
+            repository = Path(temporary_directory)
+            nested_agents = repository / "docs" / "AGENTS.md"
+            nested_agents.parent.mkdir()
+            nested_agents.write_text("nested instructions\n", encoding="utf-8")
+
+            plan = build_init_plan(repository)
+
+            self.assertEqual(plan.files[0].path, "AGENTS.md")
+            self.assertEqual(plan.files[0].action, InitPlanAction.CREATE)
+            self.assertEqual(
+                nested_agents.read_text(encoding="utf-8"),
+                "nested instructions\n",
+            )
+
+    def test_write_init_files_creates_only_root_agents_file(self) -> None:
+        with tempfile.TemporaryDirectory() as temporary_directory:
+            repository = Path(temporary_directory)
+
+            with tempfile.TemporaryDirectory() as outside_directory_name:
+                outside_agents = Path(outside_directory_name) / "AGENTS.md"
+                outside_agents.write_text("outside instructions\n", encoding="utf-8")
+
+                result = write_init_files(repository)
+
+                self.assertEqual(result.files[0].path, "AGENTS.md")
+                self.assertEqual(result.files[0].action, InitPlanAction.CREATE)
+                self.assertEqual(
+                    (repository / "AGENTS.md").read_text(encoding="utf-8"),
+                    BASELINE_AGENTS_CONTENT,
+                )
+                self.assertEqual(
+                    outside_agents.read_text(encoding="utf-8"),
+                    "outside instructions\n",
+                )
+
+    def test_write_init_files_backs_up_only_root_agents_file(self) -> None:
+        with tempfile.TemporaryDirectory() as temporary_directory:
+            repository = Path(temporary_directory)
+            root_agents = repository / "AGENTS.md"
+            nested_agents = repository / "docs" / "AGENTS.md"
+            nested_agents.parent.mkdir()
+
+            root_agents.write_text("root instructions\n", encoding="utf-8")
+            nested_agents.write_text("nested instructions\n", encoding="utf-8")
+
+            result = write_init_files(repository)
+
+            self.assertEqual(result.files[0].path, "AGENTS.md")
+            self.assertEqual(result.files[0].action, InitPlanAction.BACKUP_AND_REPLACE)
+            self.assertEqual(result.files[0].backup_path, "AGENTS.md.agent-rules-kit.bak")
+            self.assertEqual(
+                (repository / "AGENTS.md.agent-rules-kit.bak").read_text(
+                    encoding="utf-8"
+                ),
+                "root instructions\n",
+            )
+            self.assertEqual(root_agents.read_text(encoding="utf-8"), BASELINE_AGENTS_CONTENT)
+            self.assertEqual(
+                nested_agents.read_text(encoding="utf-8"),
+                "nested instructions\n",
+            )
+
+    def test_write_init_files_leaves_no_atomic_temporary_file(self) -> None:
+        with tempfile.TemporaryDirectory() as temporary_directory:
+            repository = Path(temporary_directory)
+
+            write_init_files(repository)
+
+            self.assertFalse((repository / ".AGENTS.md.agent-rules-kit.tmp").exists())
+
+
+if __name__ == "__main__":
+    unittest.main()